Heavy-quark contributions to the ratio FL/F2 at low values of the Bjorken variable x

TL;DR

This paper derives simple formulas for the ratios of heavy-quark contributions to proton structure functions at low Bjorken x, aiding the extraction of these functions from deep-inelastic scattering data.

Contribution

It provides compact, practical formulas for the ratios of heavy-quark structure functions, explaining their approximate independence from x and parton distributions at low x.

Findings

Ratios R_i are approximately independent of x at low x.

Formulas facilitate extraction of F_2^i from experimental data.

The approach clarifies the behavior of heavy-quark contributions in the low-x regime.

Abstract

We study the heavy-quark contributions to the proton structure functions $F_2^i(x,Q^2)$ and $F_L^i(x,Q^2)$, with $i=c,b$, for small values of Bjorken's $x$ variable and provide compact formulas for their ratios $R_i=F_L^i/F_2^i$ that are useful to extract $F_2^i(x,Q^2)$ from measurements of the doubly differential cross section of inclusive deep-inelastic scattering at DESY HERA. Our approach naturally explains why $R_i$ is approximately independent of $x$ and the details of the parton distribution functions in the low-$x$ regime.